Automatic lift



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K. R, WEISE AUTOMATIC LIFT Filed DGO. 5, 1931 March 24, 1936.

K. R. WEISE AUTOMATIC LIFT 4 Sheets-Sheet 2 Filed Deo. 5, 1951 v /NnS/vroe:

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March 24, 1936.

K. R. WEISE` AUTOMATIG LIFT 1931 4 sheets-Sheet 5 Filed Dec N .bm

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K. R. WEISE AUTOMATIC LIFT March 24, 1936.

Filed Dec. 5, 1931 4 Sheets-Sheet 4 E N EW .e VDN m m7 W W.

Patented Mar. 24, 1936 'y UNITED STATES PATENT yori-ica AUTOMATIC LIFT Kurt R. Wese,University Heights, Ohio, assignor to The Cleveland Crane & Engineering Company, Wickliffe, Ollio, a corporation of Ohio VApplication December 5, 1931, Serial No. 579,255

32 Claims.

The present invention relates to a transfer system and more particularly to a monorail system in which a carrier is moved from one track to another either on the same or different levels byv automatic means. In systems of the type referred to, the carrier is usually run onto a movable section of track which is subsequently aligned with the track to. which it is desired to transfer the carrier and the carrier run off. In operation, the movable section of track which is under the co-ntrol of an operator is often moved while the carrier is only partly positioned thereon, resulting in damage to the equipment and load and in un-v l matically moved from one track to another by means of a transfer section, which will be simple and economical in construction and positive and reliable in operation, and which will function without any attention whatsoever.

Another object of the invention is the provision of a control means for a transfer section in which a carrier is automatically moved from one track to another by means of a transfersection which will prevent any operation or movement of the transfer section when a carrier is improp-` erly positioned on the transfer section or adjacent tracks.

Other objectsand advantages of the invention will be apparent to those skilled in the art from the following disclosure'. of the preferred embodiment of the invention described with reference to the accompanying drawingain which:

Figure 1 is a side elevational view of a sectionV of a transfer system embodying the present invention; Fig. 2 is an enlarged'view ofthe drop section shown at the right-hand end of Fig. 1;

Fig. 3 is a view taken on the line 3-3 of Fig. 2; Fig. 4 is an enlarged elevational view of the right-hand control unit mounted on .the lower section of track shownin Fig. 1

Fig. 5 is a view taken on the line 5 5 of Fig. 4; and

carrier is automati Fig. 6 is a wiring diagram of the drop section, kg hoist motor, and-control circuits. i 'f 1 'Ihe preferred embodiment of the invention illustrated in the drawings shows a section of a monorail transfer system which includes an upper level track I0, a lower level track II, and a second upper level track I2, a drop section of 5 track I3 for lowering carriers from track I0 to track I I, and a raised section of track I4 for moving the carriers from track II to track I2. A carrier designated ingeneral by the reference character I5 is provided with front wheels I6 and I0 rear wheels I1 and is adapted to travel along the transfer system from right to left, as viewed in Fig. 1 under the action of gravity, all of the tracks sloping slightly toward the left.

The stationary tracks I0, II and I2 are sup- 15 ported in any suitable manner, as is well known in the art, such as by hangers, not shown, attached to the ceiling I8. The movable sections of track are supported by hoist cables 22 and raised and lowered by reversible hoist motors 23 20 provided with an electric brake and connected to drums 24 about which the cables 22 are wound and unwound in a manner well known in the art.

The movable sections of track I3 and I4, as they travel between the upper level tracks I0 25 and I2 and the lower level track II, are guided by vertical H-beams r25 and 26 which form part of structures 21 and 28 connecting adjacent ends of the tracks IIJ and II and tracks I I 'and I2 respectively. The H-beams 25 and 26 are engagedoY by a plurality of rollers 29 and 3U carried by members 3| and 32 pivotally connected as at 33 and 34 to brackets 35 and 36 fixed to the movable sections I3 and I4 respectively. Pins 31 carried by the brackets 35 and 36 are positioned to 'engage 35 in openings 38 in plates 39 lattached to the structure 21 and 28 at the lower ends of the H-beams 25 and 26 and aid in aligning the movable sections of track with the lower level track II.

A plurality of control units 45, 46, 41 and 48 are 40 positionedV on the track, as shown in Fig. 1, and are adapted to be operatedby the wheels of the carriers as they move along the transfer system. Each of the control units 45, 46, 41 and `48 consists of two brackets 49 and 50 suitablysecured 45 to the top of the rails and spaced from each other approximately the distance between the front and rear Wheels of the carrier I5. Short rods 5I and 52 are adjustably secured, as by means of nuts 53, to the brackets 49 and 50 respectively. 50 SwitchY boxes 54 and 55are pivotally supported as at 56 and 51 on the rods 5I and 52 respectively and are adapted to be moved about the p ivots 56Y and 51 by rods 58 and 59 pivotally connected at one end to the boxes 54 and 55, as atY 55" 60 and 6|, and at the other end pivotally connected to a trip bar 62. The rods 58 and 59 slidably supported in suitable bosses 63 and 64 on the brackets 49 and 50 and support the trip bar 62 in such a position relative to th'e track that it is engaged and lifted to pivot the switch boxes aboutthe pivots 56 and 51 by the carrier wheels I6 and I1 as the carrier moves underneath along the track. The construction is such that the switch boxes 54 and 55 are not pivoted to close or open the switches therein unless a carrier wheel is underneath the trip bar 62 adjacent the box; that is in order to pivot both boxes 54 and 55 enough to operate all the switches in any one unit, both the front and rear wheels of the carrier must be underneath the trip bar 62.

The switch boxes 54 and 55 of control unit 45 have mounted therein normally closed mercury switches 10 and 1| respectively which are opened as the boxes are pivoted by the wheels of the carrier engaging the trip bar 62. Control units V45 and 41 are identical in construction, each having a single mercury switch mounted in each switch box, and are positioned adjacent the movable sections of track I3 and I4 respectively. Reference characters 10 and 1I designate the corresponding switches in control unit 41. Control units 46 and 48, which are identical in construction, are spaced from the end of the tracks on which they are supported a distance approximately equal to the length of the movable sections and differ from units 45 and 41 in that each switch box carries two mercury switches instead of one. Mercury switch 12 normally open and mercury switch 13 normally closed are mounted in switch box 54, and mercury switch 14 normally open and mercury switch 15 normally closed are mounted in switch box 55 of control unit 46. The corresponding switches in control unit 48 are designated by the reference characters 12', 13', 14' and 'I5'.

Stops which normally engage the tread of the rail are pivotally carried by brackets 50 of control units 46 and 48 and prevent reverse movement of the carrier once the wheels have passed the stops. Stops 8| are pivotally mounted on the movable sections of track adjacent one end thereof. The stops 8| freely swing in one direction about their pivot, as they are engaged by the wheels of the carrier and permit the wheels to pass thereby, but movement of the stops 8| in the reverse direction is prevented by a projection 82 in the path of said stops. A stop 83 is slidably supported by the structure 21 adjacent the end of track I0 and projects in the path of the carrier wheels when the drop section |3 is not in alignment with track I0. As the drop section of track I3 moves into its up position, an abutment 84 of stop 83 engages the top of the section and raises stop 83 clear of the carrier wheels. VA similar stop 85 is provided at the open end of track I2.

A stop 86 similar to stop 83 is slidably mounted in the drop section I3 at the end remote from stop 8| and prevents a carrier positioned on the drop section from running off the lefthand end, as viewed in Figs. 1 and 2. A projection 81 on stop 86 engages the plate 39 as the drop section I3 approaches its lower position and raises the stop clear of the wheels so that a carrier positioned thereon may run off the section onto track A stop 90, comprising a pair of arms pivoted in the H-beam25 near the track I I, prevents a carrier'from backing off the track II when the drop section I3 is not in alignment therewith. The arms which comprise stop 90 are swung about their pivots to clear the wheels of a carrier by the engagement of the lower part of the member 3| with the top part thereof as the drop section I3 moves into its lower position. Similar stops 9| and 92 are positioned at the lefthand end of track II and raise section I4, as viewed in Fig. l.

Normally closed limit switches and 66 are attached to the structure 21 and 28 in such a position that they are engaged and opened by the drop and raised sections I3 and I4 respectively as they reach their up positions. Normally closed limit switches 91 and 98 are adjustably attached to plates 99 and |00 carried by the H-beams 25 and 26 and are engaged and opened by cam members |0| and |02 on the members 3| and 32 respectively as the drop and raised sections I3 and I4 reach their down position. Normally open mercury switches |03 and |04 are mounted in switch boxes |05 and |06 pivotally carried by the drop'and raisesections I3 and I4 in the path of the wheels of a carrier. As the wheels of a carrier engage the switch boxes |05 and |06, they are rotated about their pivots and the Switches |03 and |04 are closed.- Switches |03 and |04 are connected to the control circuit by cables |01 and |08 respectively. Take-up reels |09 and ||0 supported on the ceiling are used to keep the cables taut at all times so that they will not obstruct the passage of the carriers along the transfer system.

. Fig. 6 shows a schematic wiring diagram of the hoist motor and control circuit for the drop section I3. The motor is a conventional reversible type direct current motor, the supply of current to which is controlled by solenoid operated contactors I|5 and I|6. When the contactors I|5 are closed, the motor is rotated to lower the drop section I3, and when the contactors ||5 are closed, the motor is rotated to return the drop section to its up position. The contactors are mounted on a control panel ||1 and have an interlock I|4 to prevent both circuits being closed at the same time. The location of the various limit switches and mercury switches previously referred to in the up and down control circuits ||8 and IIB respectively is shown in Fig. 6. Circuits |20 and I2| connected to auxiliary contacts on the contactors ||5 and ||5 are holding in circuits for the up and down solenoids |22 and |23 respectively. The holding incircuits |20 and I2| are employed to continue the movement of the drop section in either direction once it has started until stopped by the limit switches 95 or 91, independent of the other switches.

The operating circuits of both hoist motors are identical with the exception that the raise circuit of one will be the lower circuit of the other, .and vice lversa.

The operation of: the system is as follows: Assuming that the parts are in the relative positions shown in Fig. 1, with the carrier I5 moving from right to left, the hoist motor 23 is inoperative and the brake is applied to hold the drop section I3 in its up position. Mercury switches 10 and 1| are open due tothe engagement of the trip bar 62 of the control unit 45 with the wheels of the carrier I5. The movement vof the carrier continues until the front wheels I6 strike the stop B6. Before the .front wheels I6 reach stop 86 the rear wheels |1 clear the trip bar 62 on control unit.4.5`al1owing it to drop and close mercury switches 10 and 1I which are in series with mercury switch |03. Asl the rear wheelsl I'I pass the stop 8|, it drops behind them and the carrier is securely locked on the drop section. As the front wheels I6 engage the stop 86, the switch box |05 is pivoted by the front wheels I6 and the mercury switch: |03 closes, energizing the motor 23 to lower the drop section. As the drop section I3 approaches its down position, cam I 0I opens the limit switch 91 to stop the motor and apply the brake.

The stops ,86 and are now clear of thecarriage wheels and the carriage runs oi the drop section onto the track II. As the carriage passes under the control unit 46, and while both the front and rear wheels are underneath the trip bar 62, mercury switches 'I2 and 'I4 are closed by the engagement of the front and rear wheels with the trip rod 62. Switches 12 and 'I4 which are in series in the raise circuit to the motor close the same and the drop section returns to its up position where it is stopped by the limit switch 95 which is opened by the engagement of the drop section I3 therewith. As the drop section moves away from the down position the stop 90 again projects in the path of the carrier wheels and prevents the carrier from backing off the rail.

Mercury-switches 13 and 'I5 are in series,/and if either of these switches is open due to engagement of the trip bar 62 of the control unit 46 with either a -front or rear carrier wheel the drop section is prevented from lowering even though the mercury switch |03 is closed by a carrier positioned on the drop section I3 until the car-y rier on the lower level has passed completely underneath the control unit 46. Once the carrier passes the control unit 46, it is prevented from backing up under the trip bar by the stop 80.

The operation of the raise section I4 is substantially the same as that of the drop section I3, and it is considered unnecessary to describe it in detail.

' The embodiment of the invention illustrated and described is merely the preferred form, andY I do not Wish to be limited to the particular construction shown. 'Ihe word reciprocable or its derivatives, as used throughout the claims, is intended to cover an oscillatory as well as a lineal movement, and I particularly point out and claim as my invention:

1. In a transfer system. the combination of a track, a second track, a reciprocable section of track' adapted to be aligned with either of said tracks, means adapted to move said section from alignment with one track into alignment with the other to transfer a carrier from one track to the other, and means adapted to prevent movement of said section when a carrier is positioned on either of said tracks adjacent said movable section.

2. In a transfer system, the combination of a track, a second track, a reciprocable section of track adapted to be aligned with either of said tracks, means for moving said section from alignment with one track into alignment with the other to transfer a carrier from one track to the other, and control means on one of saidv tracks for the rst mentioned means to preventl operation of said section when a carrier is positioned on one of said tracks adjacent the movable section.

3. In a transfer system, the combination of a track, a second track, a movable section of track `adapted to be aligned with either of said tracks,

means adapted to move said section from alignment Withone track into alignment with the other to transfer a carrier from one track to the other, control means on said section for said first mentioned means, said control means being adapted to be operated by a carrier positioned on said section for moving said section, means supported by said tracks adapted to prevent a carrier from backing up on said system, and means supported by said tracks adapted to prevent operation of said section when a carrier is positionedon one of said tracks adjacent said movable section.

4. In a transfer system, the combination of a track, a second track, a reciprocable section of track, means for moving said section from alignment with one of said tracks into alignment with the other, and means on said second track to pre vent movement of said section when a carrier is positioned on the second track adjacent the movable section.

5. In a transfer system, the combination of a track, a second track, a movable section of track, means adapted to move said section from alignment with one of said tracks into alignment with the other, automatic means positioned on said section adapted to automatically operate said first mentioned means when a carrier has been positioned on said section, and means supported by said tracks adapted to be controlled by a carrier and adapted to prevent operation of said movable section when a carrier is positioned on one of said tracks adjacent said movable section.

6. In a transfer system, the combination of a track, a second track, a reciprocable section of track adapted to be aligned with either of said tracks, a motor adapted to move said section from alignment with one track into alignment with the other, a control circuit for said motor, and switches in said control circuit actuated by a carrier on said system adapted to automatically operate said motor to move said section from alignment with one of said tracks into alignment with the other, and means on one of said tracks adapted to prevent operation of said first mentioned means while a carrier is positioned on one of said tracks adjacent said movable section.

8. In a transfer system, the combination of a track, a second track, a movable section of track, means for moving said section from alignment with one of said tracks into alignmentwith the other, means on said section for operating said rst mentioned means, and means on said tracks for preventing `operation of said means when a carrier is positioned on one of said tracks adjacent said section.

9. In a transfer system, a track, a second track spaced laterally from said first mentioned track, a movable section of track, means including a motor for moving said section into alignment with either of said tracks, a control circuit for said motor, means on said section for closing said circuit adapted to be operated by a carrier on 4 track spaced laterally from said first mentioned track, a movable section of track, means including a motor for moving said section into alignment with either of said tracksa control circuit for said motor, means on said section for closing said circuit adapted to be operated by a carrier on said section, and means on one of said tracks adapted to open said circuit when a carrier is positioned on said track adjacent said section.

11. In a transfer system, a track, a second track vertically positioned with reference to said first mentionedV track, a movable section of track adapted to be aligned with either of said tracks, a motor for moving said section, a control circuit for operating said motor, means on said section for closing said circu't adapted to be operated by a carrier, and means for opening said circuit when a carrier is positioned on said tracks adjacent said section.

12.In a transfer system, a track, a second track vertically Ypositioned with reference to said first mentioned track, a movable section of track adapted to be aligned with either of said tracks,

` a reversible motor for moving said section, a control circuit for operating said motor in one direction, a second control circuit for operating said motor in the other direction, means on said section adapted to be operated by a carrier for closing said first mentioned circuit, means for opening said circuit when a carrier is positioned on said tracks adjacent said section, and means on said second track adapted to be operated by a carrier for closing Vsaid second circuit.

13. In a transfer system, a track, a second l track laterally spaced from said track, a movable section of track adapted to be aligned with either of said tracks, a carrier adapted to be moved along said tracks and section, a motor for moving said section, a control circuit for operating said motor, means for opening said circuit as said carrier is moved onto said section, and means on said section for closing said circuit when said carrier is positioned on said section.

14. In a transfer system, a track, a second track laterally spaced from said track, a movable section of track adapted to be aligned with either of said tracks, a carrier adapted to be moved along said tracks and section, a reversible motor for moving said section, a control circuit for operating said motor in one direction, a second control circuit for operating said motor in the other direction, means for opening said first mentioned circuit as said carrier is moved onto said section, means on said section for closing said first mentioned circuit when said carrier is positioned on said section, and means on said second track for closing said second circuit after the carrier has moved off of said section onto said second track.

15. An overhead transfer system comprising an overhead track, a second overhead track, a movable section of overhead track adapted to be aligned with either of said overhead tracks, means for moving said 'section from alignment with one of said overhead tracks into alignment with the other` thereof, whereby a carrier is transferred from one Vof said overhead tracks to the other, and means adapted to prevent movement of said section when a carrier is positioned on either of said tracks adjacent said movable section.

' 16. An overhead transfer system comprising an overhead track, a second overhead track, a movable sectionl of overhead track adapted to spaanse be aligned with either 'of said overhead tracks, means for moving said section from alignment With one of said overhead tracks into alignment with the other thereof, whereby a carrier is transferred from one of said overhead tracks to the other, and control means on one of said overhead tracks for the first mentioned means to prevent operation of said means when a carrier is positioned on one of said overhead tracks adjacent said movable section.

17. An overhead transfer system comprising an overhead track, a second overhead track, a movable section of overhead track adapted to be aligned with either of said overhead tracks, means for moving said section from alignment with one of said overhead tracks into alignment with the other including a motor, a control circuit for said motor, and switches in said control circuit adapted to be actuated by the movement of a carrier along said overhead tracks adapted to control the operation of said motor and to prevent operation of said motor when a carrier engages one of said tracks adjacent said movable section.

18. An overhead transfer system comprising an overhead track, a second overhead track, a movable section of overhead track, means for moving said section from alignment with one of said overhead tracks into alignment with the other, means on said section for operating said first mentioned means, and means on said overhead tracks for preventing operation of said means when a carrier is positioned on one of said overhead tracks adjacent said section.

19. An overhead transfer system comprising an overhead track, a second overhead track vertically positioned with reference to said first mentioned overhead track, a movable section of overhead track adapted to be aligned with either of said overhead tracks, a reversible motor for moving said section, a control circuit for operating said motor in one direction, a second control circuit for operating said motor in the opposite direction, means on said section adapted to be operated by a carrier positioned thereon for closing said first mentioned circuit, means for opening said first mentioned circuit when a carrier is positioned on said overhead tracks adjacent said section, and means on said second overhead track adapted to be operated by a carrier positioned thereon for closing said second circuit.

20. An overhead transfer system comprising an overhead track, a second overhead track vertically positioned with reference to said first :s

mentioned overhead track, a movable section of overhead track adapted to be aligned with either of said overhead tracks, a carrier adapted to be moved along said overhead tracks and section, means including a motor for moving said section, a control circuit for said motor, means for opening said circuit as said carrier is moved onto said section, and means on said section for closing said circuit when said carrier is positioned on said section.

21. An overhead transfer system comprising an overhead track, a second overhead track vertically spaced from said first overhead track, a movable section of overhead track adapted to beV aligned with either of said overhead tracks, a

carrier adapted to be moved along said overhead tracks and section, means for moving said section including a reversible motor, a control circuit for operating said motor in one direction, a second control circuit for operating said motor in the reverse direction, means for opening said first mentioned circuit as said carrier is moved onto said section, means on said section' for closing said rst mentioned circuit when said carrier is positioned on said section, and means on said vsecond overheadV track for closingl said second circuit after the carrier has moved olf of said section onto said section track.

22. In a transfer system, the combination of a track, a movable section of track adapted to be aligned with either of said tracks, 'an electric motor adapted to move said movable section of track from alignment with either of said tracks into alignmentwith the other of said tracks, a carrier adapted to travel along said track, a member pivotally supported adjacent one of said tracks adapted to simultaneously engage spaced points on said carrier, and means adapted to energize said motor actuated by the lengagement of said member by a plurality of points on said carrier. l I,

23. In a transfer system, the combination of a track, a movable section of trackadapted to be aligned with either of said tracks, an electric motor adapted to move said movable section of track from alignment with either'of said tracks into alignment with the other of said tracks, a carrier adapted to travel along' saidtrackfa member pivotally supported adjacent one'of said tracks adapted to simultaneously engage spaced points on said carrier, a carrier'provided with front and rear wheels adapted' to travel along said tracks, a member pivotally supported adjacent one of said tracks adapted to simultaneously engage the front and rear wheelsof'said carrier, and means adapted to energize saidmotor when said member is simultaneously engaged by both front and rear wheels of said carrier.

24. In a transfer system, the combination of a track, a movable sectionof track adapted to. be aligned with either of said tracks, an electric motor adapted to move'said movable section of track from alignment with either of said tracks into alignment with the other of said tracks, a carrier `adapted to travel along said track, a member pivotally supported adjacent one of said tracks adapted to simultaneously engage spaced points on said carrier, and means adapted to open the circuit to said motor actuated by the engagement of said member by any part of said carrier.

25. In a transfer system, the combination of a track, a movable section of track adapted to be aligned with either of said tracks, an electric motor adapted to move said movable section of track from alignment with either of said tracks into alignment with the other of said tracks, a carrier adapted to travel along said track, a member pivotally supported adjacent one of said tracks adapted to simultaneously engage spaced points on said carrier, a carrier provided with front and rear wheels adapted to travel along said tracks, a member pivotally supported adjacent one of said tracks adapted to simultaneously engage the front and rear Wheels of said carrier, and means adapted to open the circuit to said motor when said member is engaged by either a front or rear wheel of said carrier.

26. A transfer system comprising, a rst track, a second track, a movable section of track adapted to be aligned with 'either of said tracks, a reversible electric motor adapted to move said movable section of track from alignment with either of said tracks into alignment with the other f said tracks, a first control circuit for said motor adapted to actuate said motor to move said movable section of track from alignment with said first track into alignment with said second track, a second control circuit for said motor adapted to actuate said motor in the reverse direction to return said movable section of track into alignment with said first track, a normally closed switch in said rst control circuit, means adapted to open said normally closed switch adapted to be actuated by a carrier positioned on said first track, a normally-open switch in said second control circuit supported by said second track, and means adapted to close said normally open switch adapted to be actuated by a carrier positioned on saidsecond track.

27. A transfer system comprising a rst track, a second track, a movable section of track adapted to be aligned with either of said tracks, an electric motor adapted to move said movable section of track from alignment with either of said tracks' intoV alignment with the other of said tracks, a first control circuit for said motor adapted to actuate said motor to move said movable section of track from alignment'with lsaid first track into alignment with said second track, a second control circuit for said motor adapted to actuate said motor in a reverse direction to return said movable section. of track into alignment with said rst track,` a normally closed switch in said first control circuit, means adapted to open'said normally closed switch adapted to be actuatedbya carrier positioned on said rst track adjacent said movable section of track, a normally open switch in said second control circuit, means adapted to close said normally open switch adapted t0 be actuated by a carrier positioned on saidsecond track adjacent said movable section of track,v and means adapted to prevent a carrier from backing up and actuating said last mentioned means once it has passed thereby.

28. A transfer system comprising a rst track, a. movable section of track adapted to be aligned with either of said tracks,

mean'sadapted to movesaid movable section of track from alignment with either of said tracks into alignment with the other of said tracks, said means including a reversible electric motor, a lrst control circuit for said motor adapted to actuate said motor to move said movable section of track from alignment with said rst track into alignment with said second track, a second control circuit for said motor adapted to actuate7 said motor in a reverse direction to return said movable section of track into alignment with said first track, a normally closed switch in said rst control circuit, means adapted to open said normally closed switch adapted to be actuated by a carrier positioned on said rst track adjacent section of track, a normally open switch in said second control circuit, means adapted to close said normally open switch adapted to be actuated by a carrier positioned on track adjacent said movable secand a stop adapted to prevent a carrier from backing up and actuating said last mentioned means once it has passed thereby.

29. A transfer system comprising, a rst track, a second track, a movable section of track adapted to be aligned with either of said tracks, means adapted to move said movable section of track from alignment with either of said tracks into alignment with the other of said tracks, said means including a reversible electric motor, a rst control circuit for said motor adapted to actuate said motor to move said movable section of track from alignment with said rst track Vinto alignment with said second track, a second control circuit for said motor adapted to actuate said motor in the reverse `direction to return said movable section of track into alignment with said first track, a normally closed switch in said first control circuit, means adapted to open said normally closed switch adapted to be actuated by a carrier positioned on said rst` track adjacent said movable section, a second normally closed switch in said irst control circuit, means adapted to open said second normally closed switch adapted to be actuated by a carrier positioned on said second track, a normally open switch in said second control circuit, and means adapted to close said normally open switch adapted to be actuated by afcarrier positioned on said second track.

30. A transfer system comprising, a rst track, a secondtrack, a movable section of track adapted to be aligned with either of said tracks, an electric motor adapted to move said movable'section of track fromy alignment with either of said tracks into alignment with the other of said tracks, a rst controlY circuit for said motor adapted to actuate said motor to move said movable section of track from alignment with'said first track into alignment with said second track, a second control circuit for said motor adapted to actuate said motor in the reverse direction to return said movable section of track into alignment -with said first track, a normally closed switch in said first control circuit, means adapted to open said normally closed switch adapted to be actuated by a carrier positioned on said first track, a second normally closed switch in said rst control circuit, means adapted to open said second normally closed switch adapted to be actuated by a carrier positioned on saidsecond track, a normally open switch in said second control circuit, means adapted to close said normally open switch adapted to be actuated by a carrier positioned on said second track, and means adapted to prevent a carrier from backing up and actuating said last mentioned means after it has passed thereby. Y

31.V A transfer system comprising a first track, a second track, a movable section of track adapted to be aligned with either of said tracks, an electric motor adapted to move said movable section of track from alignment with either of said tracks into alignment with the other of said tracks, a first control circuit for said motor adapted to actuate said motor to move said movable section of track from alignment with said first track into alignment with said second track, a second control circuit for said motor adapted to actuate said motor in a reverse direction to return said movable section of track into alignment with said first track, a normally closed switch in said first control circuit supported by said rst track adjacent said movable section of track, means adapted to open said normally closed switch when a carrier is positioned on said rst track adjacent said movable section of track, a second normally closed switch in said first circuit supported by said second track, means adapted to open said second normally closed switch when a carrier is positioned on said second track adjacent said movable section of track, a normally open switch in said second control circuit supported by said second track, means actuated by a carrier adapted to close said normally open switch when a carrier is positioned on said second track, and a movable member supported by said second track adapted to prevent a carrier from backing up and actuating said last two mentioned means once it has passed thereby.

32. An overhead transfer system comprising an overhead track, a second overhead track spaced laterally from said iirst mentioned overhead track, a movable section of overhead track, means including an electric motor for moving said section into alignment with either of said overhead tracks, a control circuit for said motor, means for closing said circuit, and means on one of said overhead tracks operated by a carrier positioned thereon for opening said circuit while the carrier is moving onto said section. 

